I own an NDX2 and I am very happy with its performance. But, it only has Tidal, Spotify and Qobuz.
A good number of budget streamers (Wiim, Node, etc) are able to offer many more streaming services, like Amazon, deezer, etc.
They do all of this in a sub 1000$ streamer, and pay the licensing fees. Why can’t Naim do as much, when charging many times their price?
Whilst I can’t answer the question, you’re paying for the quality of the streamer and its sound quality, and maybe a bit of a premium because of the brand name and the fact that it is a relatively small business based in Britain.
My understanding is that each service has its own software requirement, incorporated in the streamer’s firmware, so whenever a new service appears there is new code to write/add, and in a premium sound quality product check and double check that it doesn’t adversely affect the sound quality of anything else. And IIUC Naim doesn’t have a huge coding department, given that the number of products is small and new products far between. The consequence as I understand it - but I’m sure others can be more definitive, is that it once there is a new streaming kid on the block takes a long time to add it in, first waiting to be sure pf stability and customer interest, then doing the work and building a firmware update release. But I think they will come in due course - at least you don’t have the Mk1, with no memory left for any additional platforms!
Check what services are available via Chromecast.
I’m sure Deezer is available.
That is besides the point. Why can’t the Naim streamers have it natively in the streamer, like many less costly streamers do?
I would guess there’s a quality issue here - Naim wishing to focus on the best services, particularly for SQ, but perhaps it’s best for someone like @Stevesky to give some insight into Naim’s rationale here.
Not really you have the selected services plus ability to stream using chromecast or airplay. the list of services is endless, and the problems with supporting many of them are the same. My first streamer a Bluenode supported a lot of services but I am not really sure this made it a better streamer for that. Of course if this is important choose your streamer accordingly.
Claus
Chromecast’s lack of support for gapless playback is hugely annoying.
I’ve found the opposite.
Been using Chromecast for 4 months and only noticed the ‘no gapless’ phenomenon once. 
I have a node in my second system and am hugely impressed with its music services into my 72/hc/250. A great app and interface. Even plugging in a usb full of apparently random music is presented very well.
I have a node going into a gustard dac which directly feeds meridian M2s. Its 80% of my listening as its in my office and it sounds great.
Size of development team + R&D budget + targeted quality of result scopes the limits of what you can do and maintain. The longevity of Naim streamers is very long, and there are enough examples where support is dropped after a couple of years. You get what you pay for often.
It needs to be given the price of them. If I were to drop £2.5k on a ND5 XS2 and it was obsolete after a couple of years I’d be mightily p’d off and that would certainly put me off buying Naim in the future
Unless you only use the NDX2’s remote, an iOS tablet or phone will easily enable an app to be connected via airplay. Perhaps the Amazon app would also work like that; never used it. Those enjoying first gen streamers, if they wish to stream Qobuz, as a search will reveal, then peps use a variety of workarounds including via a NAS. There are many a work around for different services; ymmv.
There are workarounds to get Chromecast to play gapless. Whether you want to use them is your decision. I sort of backed into mine.